I noticed too that many of the companies distributing these apps have a hard time getting it right. Looking at Pioneer, they have :
All apps basically do the same, but each has a different set of supported devices. If you look at their rating, you'll see that they don't score high. I almost dismissed Pioneer for this feature, but reading the reviews I quickly found that most bad reviews are because Pioneer choose to put support for different receivers in different versions of their App. iControlAV2012 only supports the latest receivers, but still supports most of the Blu-Ray player that iContolAV2 supports as well.
Even though this is all clearly marked in the description, users are angry because it doesn't work with their device. To add to these users anger, the iOS version does support all versions supported by iContolAV, AV2 and AV2012 combined.
So how should Pioneer improve this in my opinion? I think they should release iControlAV 3.0 as a modular system. You then download the control modules for your receiver, blu-ray player and other devices separately. This also ensures I don't need to download a 40 MB file for a simple remote control.
Please pioneer, learn. Ohh and please fix the installer so that I don't have to unmount my SD card to install your app.